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WO1991012675A1 - Station de base pour systeme radio - Google Patents

Station de base pour systeme radio Download PDF

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Publication number
WO1991012675A1
WO1991012675A1 PCT/FI1991/000035 FI9100035W WO9112675A1 WO 1991012675 A1 WO1991012675 A1 WO 1991012675A1 FI 9100035 W FI9100035 W FI 9100035W WO 9112675 A1 WO9112675 A1 WO 9112675A1
Authority
WO
WIPO (PCT)
Prior art keywords
signal
base station
monitoring
monitoring signal
frequency
Prior art date
Application number
PCT/FI1991/000035
Other languages
English (en)
Inventor
Pertti Korhonen
Jukka Korhonen
Pertti Huttunen
Original Assignee
Telenokia Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telenokia Oy filed Critical Telenokia Oy
Priority to EP91914187A priority Critical patent/EP0513250B1/fr
Priority to DE69112381T priority patent/DE69112381T2/de
Publication of WO1991012675A1 publication Critical patent/WO1991012675A1/fr
Priority to NO923101A priority patent/NO301357B1/no

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/30—Monitoring; Testing of propagation channels
    • H04B17/382—Monitoring; Testing of propagation channels for resource allocation, admission control or handover
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/10—Monitoring; Testing of transmitters
    • H04B17/15—Performance testing
    • H04B17/18—Monitoring during normal operation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements

Definitions

  • the invention relates to a base station for a radio system, the base station comprising, for monitoring the quality of a radio link between a base station and mobile stations, a filter means for generating a monitoring signal from a rectangular wave signal having a desired monitoring signal frequency, the frequency of the monitoring signal being variable by varying the frequency of the rectangular signal; a transmitter means for transmitting the monitoring signal to a mobile radio station; a receiver means for receiving the monitoring signal transmitted back from the mobile radio station; signal processing means for de ⁇ termining the quality of the used radio link by means of the received monitoring signal.
  • the quality of the radio link between a base station and a mobile telephone is monitored by means of special monitoring signals.
  • the base station generates the monitoring signal by low-pass filtration from a clock signal having a desired monitoring signal frequency.
  • the NMT system utilizes four monitoring signal frequencies at intervals of 30 Hz.
  • the base station transmits a monitoring signal to a mobile telephone which returns the monitoring signal immediately to the base station, and the base station determines the quality of the used radio link, especially the signal-noise ratio, by means of the received monitoring signal.
  • the apparatus which generates the monitoring signal, measures the signal-noise ratio, and identifies the frequency of the monitoring signal coming to the base station is based on time continuous filters accomplished with discrete components, whereby each filter operation is performed with the same fixed filter for all four monitoring signal frequencies.
  • each filter operation is performed with the same fixed filter for all four monitoring signal frequencies.
  • there thus occurs a difference in level between the monitoring signals which becomes apparent as variation in the deviation of the monitoring signal applied from the base station to the mobile telephone.
  • the level difference of the monitoring signals also affects the measuring accuracy of the S/N ratio.
  • the base station also measures the frequency of the received monitoring signal to ensure that it measures the right mobile station. For identification purposes, it is sufficient to know whether the frequency is the right one or some of the four other possible frequencies.
  • the identification of monitor- ing signals also suffers from the above-mentioned level difference between the monitoring signals, as the identification is based on the mixing of the re ⁇ ceived monitoring signal and an injection signal positioned at an interval of 60 Hz from the monitor- ing signal, and on the bandpass filtration and detec ⁇ tion of the resulting difference signal.
  • the object of the present invention is a base station which avoids the above-mentioned drawbacks associated with monitoring signals. This is achieved according to the first embodi ⁇ ment of the invention by means of a base station which is characterized in that the filter means com ⁇ prises a filter accomplished by the Switched capacitor technique.
  • a base station according to the second embodi- ment of the invention is characterized in that the signal processing means comprise filters accomplished by the Switched capacitor technique.
  • the invention utilizes the property of filters accomplished by the Switched capacitor technique that their center and/or cut-off frequencies are dependent on the frequency of the clock signal controlling them.
  • the clock signals of the Switched capacitor filters are synchronized with a rectangular wave signal and the frequency of the clock signals varies in the same proportion as the frequency of the rectangular wave signal, the Switched capacitor filter is automatically adopted to the new monitoring signal frequency, whereby all the signal processing functions performed by the filters are identical for all monitoring signals irrespective of the frequency. Thereby the level of the monitoring signal remains constant at all the different monitoring signal frequencies.
  • the clock signals of the filters are derived from the same primary clock signal as the rectangular wave signal, that . is, the monitoring signal frequency.
  • the signals can be synchronized and a constant frequency ratio can be obtained between the signals in a simple way.
  • Switched capacitor filters already provides an improvement over prior art when used in the generation of the monitoring signals or, alternatively, in the signal processing of the received monitoring signal, the best results will be obtained by using Switched capacitor filters both in generation and reception.
  • a further advantage achieved by the Switched capacitor technique is that it enables a high integration level for the apparatus.
  • Figure 1 is block diagram of a base station portion required for the processing of monitoring signals.
  • the NMT system is a so-called cellular telephone system in which a geographical area covered by the system is divided into smaller, adjoining geographical areas or cells each comprising one or more fixed base stations in communication with mobile telephones within the cell.
  • the structure of the NMT system will not be described in greater detail herein; instead, the following citations are referred to:
  • NMT Doc.4.1981 Technical Specification for the Base Station Equipment
  • NMT Doc.900-4 Technical Specification for the Base Station Equipment
  • NMT Doc. 900-1 The above specifications are also referred to with regard to the signalling between the base station and the mobile telephone, and especially with regard to the monitoring signals.
  • the base station comprises a source generating a clock signal, such as a crystal oscil ⁇ lator 16 which applies a clock signal f c to an adjustable divider circuit 20.
  • the divider circuit 20 divides the clock signal f c by a divisor determined by a frequency setting signal FSET, thus forming a primary clock signal C K.
  • the primary clock signal CLK is divided with a fixed divider circuit 2 which produces a rectangular wave signal CK having the monitoring signal frequency and one or more filtra ⁇ tion clock signals mCK the frequency of which is pre ⁇ ferably the multiple of the frequency of the signal CK.
  • the rectangular wave signal CK is low-pass filtered by a low-pass filtration block 1 which contains a Switched capacitor low-pass filter and level adjustment.
  • the SC filter is controlled by the clock signal mCK, whereby its cut-off frequency is automatically adopted to the frequency of the rect ⁇ angular wave signals.
  • An output signal from the filtration block 1 is a sinusoidal monitoring signal CS T , which in normal operation is applied through a switch unit 14 to a time continuous low-pass filter 12 which filters the clock signal mCK from the monitoring signal.
  • An output signal from the filter 12 is applied to a transmitter unit 15 at the base station to be transmitted through a transmitter antenna 18 to a mobile radio station.
  • the monitoring signal CS T is also applied to a level indicator 13 which monitors the level of the monitoring signal, thus ensuring that it is in a window between predetermined limit values. If the level of the monitoring signal falls outside this window, the indicator 13 generates a signal Xg which can be used e.g. for the control of the level adjust- ment of the block 1.
  • the monitoring signal returned from the mobile station and received at the base station by a receiver antenna 19 a d a receiver portion 17 is low- pass filtered by a normal time continuous low-pass filter 11 which limits the upper end of the frequency band of the monitoring signal so as to prevent aliasing at subsequent stages.
  • An output signal from the filter 11 is filtered by the Switched capacitor bandpass filter to make the monitoring signal more distinguishable from the noise.
  • the center frequency of the bandpass filter 3 automatically obtains a value suitable for the monitoring signal frequency, as the filter is clocked by means of the above- mentioned clock signal mCK.
  • the received monitoring signal CS R at the output of the filter 3 is applied through the switch unit 14 to a mixer 4 and a bandpass filter 5.
  • the received monitoring signal CS R is mixed with the transmitted monitoring signal CS T or another injection signal having the monitoring signal frequency, whereby the difference frequency is zero and only a noise signal and the sum frequency of the mixed signals, in this case twice the monitoring signal frequency, occur at the output of the mixer.
  • the sum frequency and the dc component are filtered from the noise signal by the dc blocking and the Switched capacitor low-pass filter 10, which results in the formation of a signal Y- ⁇ proportional to the noise around the monitoring signal frequency.
  • the low-pass filter 10 is controlled by means of the above-mentioned clock signal mCK, whereby its cut-off frequency is automatically adjusted to a value suit ⁇ able for each monitoring signal frequency.
  • the control signal CS R received in the other branch is filtered with the twopath-type bandpass filter 5 having an adjustable bandwidth, preferably below 1 Hz.
  • the filtration is, however, started with a proportionally wider bandwidth from which the band- width is decreased to a suitable value, e.g., through three steps during 100 ms.
  • the bandpass filter 5 is controlled by means of the above-mentioned clock signal mCK, which determines its center frequency.
  • the bandpass filter 5 filters noise from the received monitoring signal CS R , which gives as a result a pure monitoring signal Y 2 .
  • the signal Y 2 is further band ⁇ pass filtered with a Switched capacitor bandpass filter 6 having a wider passba ⁇ d than the filter 5 in order to filter the harmonic frequencies formed in the filter 5 from the signal Y 2 «
  • the filter 6 is also controlled by the above-mentioned clock signal mCK.
  • An output signal Y3. from the filter 6 and the noise signal Y ⁇ are both applied to two signal processing blocks 8 and 9, in which the signal is amplified, rectified, low-pass filtered, decimated, integrated and finally the dc voltages proportional to the signals are compared.
  • a threshold value for the S/N ratio can be set, whereby the comparison result indicates whether the S/N ratio is above or below this threshold value.
  • the S/N ratio may have two monitoring threshold values: the upper threshold value, which is within the range from 10 to 40 dB, indicates that the quality of the radio link is so poor that it is advisable to establish a new radio link, and the lower threshold value, which is in the range from -5 to +10 dB, causes the call to be disconnected if a better radio link has not been found.
  • the upper threshold value which is within the range from 10 to 40 dB
  • the lower threshold value which is in the range from -5 to +10 dB, causes the call to be disconnected if a better radio link has not been found.
  • the received monitoring signal is identified by monitoring the level of the output signal Y3 of the bandpass filter 6 by means of the level indicator 7.
  • the level indicator 7 compares the level of the signal Y 2 with a predetermined threshold value and identifies the received monitoring signal if the level of the signal exceeds the predetermined threshold level.
  • the internal structure of the Switched capacitor filters used in the invention is known to one skilled in the art.
  • the basic idea of the Switched capacitor technique is that resistance can be simulated by means of a capacitor and switches, that is, when the resistance R of a so-called "normal" RC filter structure is replaced with this kind of structure, the filler parameters can be de ⁇ termined by the relations of the capacitances and the clock frequency controlling the switches.
  • the structure and implementation of the Switched capacitor filters "Analog MOS Integrated Circuits for Signal Processing", R. Gregorian & G.C. Temes, Wiley, 1986 (p. 265-296) is referred to.
  • the monitoring signal CS T to be transmitted can be applied directly to the mixer 4 and to the bandpass filter 5, when there is no speech communication between the mobile radio station and the base station.
  • the drawing and the description related to it are only intended to illustrate the present inven ⁇ tion.
  • the base station of the inven ⁇ tion may vary within the scope of the attached claims.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Selective Calling Equipment (AREA)
  • Liquid Developers In Electrophotography (AREA)
  • Exchange Systems With Centralized Control (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
  • Monitoring And Testing Of Transmission In General (AREA)

Abstract

L'invention se rapporte à une station de base pour système radio, qui, pour permettre le contrôle de la qualité d'une liaison entre une station de base et des stations mobiles, comprend: un filtre passe-bas (1, 2, 16) générant un signal de contrôle à partir d'un signal d'onde rectangulaire (CK) ayant une fréquence de signal de contrôle désirée, la fréquence du signal de contrôle étant variable en fonction de la variation de la fréquence du signal rectangulaire; un émetteur (15) servant à émettre le signal de contrôle vers une station radio-mobile; un récepteur (17) destiné à recevoir le signal de contrôle transmis en retour depuis la station radio-mobile; et un processeur de signaux (3 à 11) servant à déterminer la qualité de la liaison radio utilisée au moyen d'un signal de contrôle reçu. Pour empêcher la différence de niveau entre les signaux de contrôle ayant différentes fréquences, le filtre passe-bas (1) et au moins une partie des filtres contenus dans le processeur de signaux sont constitués, dans la station de base, par des filtres à condensateurs commutés, qui sont commandés par un signal d'horloge (mCK) tiré de la même horloge primaire que le signal d'onde rectangulaire (CK).
PCT/FI1991/000035 1990-02-08 1991-02-06 Station de base pour systeme radio WO1991012675A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP91914187A EP0513250B1 (fr) 1990-02-08 1991-02-06 Station de base pour systeme radio
DE69112381T DE69112381T2 (de) 1990-02-08 1991-02-06 Basisstation für funksystem.
NO923101A NO301357B1 (no) 1990-02-08 1992-08-07 Basisstasjon for et radiosystem

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI900620A FI84539C (fi) 1990-02-08 1990-02-08 Basstation foer ett radiosystem.
FI900620 1990-02-08

Publications (1)

Publication Number Publication Date
WO1991012675A1 true WO1991012675A1 (fr) 1991-08-22

Family

ID=8529853

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1991/000035 WO1991012675A1 (fr) 1990-02-08 1991-02-06 Station de base pour systeme radio

Country Status (7)

Country Link
EP (1) EP0513250B1 (fr)
AT (1) ATE126952T1 (fr)
AU (1) AU645115B2 (fr)
DE (1) DE69112381T2 (fr)
FI (1) FI84539C (fr)
NO (1) NO301357B1 (fr)
WO (1) WO1991012675A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992022963A1 (fr) * 1991-06-11 1992-12-23 Nokia Telecommunications Oy Station fixe pour systeme de radiocommunication a systeme de controle de la qualite des canaux radioelectriques
GB2266432A (en) * 1992-04-21 1993-10-27 Televerket An arrangement for comparing subjective dialogue quality in mobile telephone systems
EP0722226A1 (fr) * 1995-01-10 1996-07-17 Nokia Mobile Phones Ltd. Procédé et circuit pour filtrer le bruit parasite dans des récepteurs radio
US6922551B1 (en) 1998-07-15 2005-07-26 Telefonaktiebolaget L M Ericsson (Publ) Interference prevention in a radio communications system
US9479268B2 (en) * 2013-07-31 2016-10-25 Cellco Partnership Filtering interference in wireless networks

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI86017C (fi) * 1990-11-02 1992-06-25 Telenokia Oy Basstation foer ett radiosystem.

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0130873A1 (fr) * 1983-06-24 1985-01-09 Thomson Semiconducteurs Filtre passe-bande à capacités commutées
EP0164108A2 (fr) * 1984-06-07 1985-12-11 Nec Corporation Filtre à capacités commutées à caractéristique de filtrage variable

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0130873A1 (fr) * 1983-06-24 1985-01-09 Thomson Semiconducteurs Filtre passe-bande à capacités commutées
EP0164108A2 (fr) * 1984-06-07 1985-12-11 Nec Corporation Filtre à capacités commutées à caractéristique de filtrage variable

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, Vol 11, No. 11, E470, Abstract of JP 61-184 935, publ 1986-08-18 OKI ELECTRIC IND CO LTD. *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992022963A1 (fr) * 1991-06-11 1992-12-23 Nokia Telecommunications Oy Station fixe pour systeme de radiocommunication a systeme de controle de la qualite des canaux radioelectriques
AU652259B2 (en) * 1991-06-11 1994-08-18 Nokia Telecommunications Oy Base station for a radio system with arrangement for monitoring quality of radio-transmission channels
US5487178A (en) * 1991-06-11 1996-01-23 Nokia Telecommunications Oy Radio system base station including provision for generating and processing both analog and digital radio link quality monitoring signals
GB2266432A (en) * 1992-04-21 1993-10-27 Televerket An arrangement for comparing subjective dialogue quality in mobile telephone systems
GB2266432B (en) * 1992-04-21 1995-07-19 Televerket An arrangement for comparing subjective dialogue quality in mobile telephone systems
EP0722226A1 (fr) * 1995-01-10 1996-07-17 Nokia Mobile Phones Ltd. Procédé et circuit pour filtrer le bruit parasite dans des récepteurs radio
US5809399A (en) * 1995-01-10 1998-09-15 Nokia Mobile Phones Limited Method and circuit for filtering disturbances in a radio receiver
US6922551B1 (en) 1998-07-15 2005-07-26 Telefonaktiebolaget L M Ericsson (Publ) Interference prevention in a radio communications system
US9479268B2 (en) * 2013-07-31 2016-10-25 Cellco Partnership Filtering interference in wireless networks

Also Published As

Publication number Publication date
NO923101L (no) 1992-10-07
ATE126952T1 (de) 1995-09-15
FI84539C (fi) 1991-12-10
NO923101D0 (no) 1992-08-07
DE69112381D1 (de) 1995-09-28
AU8295991A (en) 1991-09-03
EP0513250B1 (fr) 1995-08-23
EP0513250A1 (fr) 1992-11-19
FI900620A0 (fi) 1990-02-08
DE69112381T2 (de) 1996-03-07
NO301357B1 (no) 1997-10-13
AU645115B2 (en) 1994-01-06
FI84539B (fi) 1991-08-30
FI900620A7 (fi) 1991-08-09

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